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Historical Glacier and Climate Fluctuations at Mount Hood, Oregon

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Abstract

Terminus fluctuations of five glaciers and the correspondence of these fluctuations to temperature and precipitation patterns were assessed at Oregon's Mount Hood over the period 1901-2001. Historical photographs, descriptions, and climate data, combined with contemporary GPS measurements and GIS analysis, revealed that each glacier experienced overall retreat, ranging from � 62 m at the Newton Clark Glacier to � 1102 m at the Ladd Glacier. Within this overall trend, Mount Hood's glaciers experienced two periods each of retreat and advance. Glaciers retreated between 1901 and 1946 in response to rising temperatures and declining precipitation. A mid-century cool, wet period led to glacier advances. Glaciers retreated from the late 1970s to the mid-1990s as a result of rising temperatures and generally declining precipitation. High precipitation in the late 1990s caused slight advances in 2000 and 2001. The general correspondence of Mount Hood's glacier terminus fluctuations with glaciers in Washington and Oregon suggests that regional, decadal-scale weather and climate events, driven by the Pacific Decadal Oscillation, play a key role in shaping atmosphere-cryosphere interactions in Pacific Northwest mountains. Deviations from the general glacier fluctuation pattern may arise from local differences in glacier aspect, altitude, size, and steepness as well as volcanic and geothermal activity, topography, and debris cover.

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... Hood, Oregon, the areas of seven glaciers have decreased by an average of 34% from 1907 to 2004 (Jackson and Fountain 2007). The glaciers retreated from 1900 until the 1950s and then either retreated at a slower rate or advanced slightly until the 1970s, followed by further retreat to the present (Lillquist and Walker 2006, Jackson and Fountain 2007). Glaciers on Mount Rainier, Washington decreased by 22% between 1913 and 1994 (Nylen 2004). ...
... Hood, Oregon, the areas of seven glaciers have decreased by an average of 34% from 1907 to 2004 (Jackson and Fountain 2007). The glaciers retreated from 1900 until the 1950s and then either retreated at a slower rate or advanced slightly until the 1970s, followed by further retreat to the present (Lillquist and Walker 2006, Jackson and). Glaciers on Mount Rainier, Washington decreased by 22% between 1913 and 1994 (Nylen 2004). ...
... The main driver of glacier recession appears to be summer air temperature, as little change in precipitation has occurred over the past century. All three temperature data sets show a significant increase in summer temperature beginning around the 1980s (e.g., Nylen 2004, Lilliquist and Walker 2006) corresponding to the rapid retreat in glacier area during the latter part of the 20th century for several studies. This is noted also in Colorado (Hoffman et al. 2007) and in Montana (Key et al 2002).Figure 4. Comparison of winter (Dec-Feb) precipitation, summer (Jul-Sep) temperature, and total glacier cover on Mount Adams. ...
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Mount Adams is a large glacier-clad stratovolcano located in southern Washington, USA. We examined the area change of the 12 glaciers on the mountain during the 20th century using historical topographic maps and aerial photographs. The total glacier area decreased by 49% (31.5 km2 to 16.2 km2) from 1904 to 2006. The glaciers showed a period of retreat during the first half of the century, followed by either a slowing of retreat or an advance from the 1960s to the 1990s. Subsequently, the glaciers resumed their rapid retreat. Glaciers on Mt. Adams show similar trends to those on both Mt. Hood and Mt. Rainier. The qualitative correlation between area change and trends in winter precipitation and summer temperature indicate a largely temperature-driven glacier shrinkage as the climate warmed since the Little Ice Age of the late 19th Century. No century-scale trends were noted in precipitation but decadal-scale variations in winter precipitation appear to enhance or buffer the effects of temperature on glacier change.
... In the northwestern United States, glaciers diminished throughout the 20 th century and model simulations suggest this trend will continue through the next 100 years (Dyurgerov and Meier, 2000;Hall and Fagre, 2003). Recent studies document that Mount Hood's glaciers have decreased in length as much as 61% over the past century (Lillquist and Walker, 2006). Coe Glacier has diminished at a rate 27% slower than that of the Eliot in the last century (Jackson, 2007), and we estimate that by about 2057 its area will be about 61% of its present day area. ...
... Glaciers in Oregon, like much of the west (e.g., Nylen, 2004;Hoffman et al., 2007) have been receding since the start of the last century when observations first began (Lillquist and Walker, 2006;Jackson and Fountain, 2007). The glaciers rapidly retreated since about 1910, slowed and advanced during the 1960s to middle 1970s before retreating again in the early 1980s. ...
... Between 1901 and 2001 these glaciers lost 31% of their area (JACKSON and FOUNTAIN, 2007). Between 1901 and, Eliot Glacier lost 775 m in length (LILLQUIST and WALKER, 2006). Presently, Eliot Glacier is less than 1.6 km 2 , 3.6 km long and 800 m at its greatest width (JACKSON, 2007) (Figure 2.1). ...
... Arsenic concentrations changed from below detection in the fresh snow, with a median concentration of less than 0.09 nM, to a median ablation snow concentration of 0.20 nM. Although lack of dissolution may explain many of the enrichments in the ablation snow trace element concentrations, ongoing dry deposition is another possibility, as less than 20% of the regional precipitation occurs during the ablation season (LILLQUIST and WALKER, 2006). ...
... Five irrigation districts along the East, Middle, and West Forks of the Hood River rely on late summer snow and ice melt from six glaciers, along with reservoir storage of winter rains, to meet high water demands during the dry summer months, while maintaining sufficient in‐stream flows and cool water temperatures for threatened anadromous fish. Recent studies document that Mount Hood's glaciers have decreased as much as 61% over the past century [Lillquist and Walker, 2006] . However, there are no historical or current monitoring programs that provide measurements of the contributions of Mount Hood glaciers to streamflow, and therefore, no way to estimate the potential impact of their loss. ...
... Our model sensitivity study shows that a 10–20% uncertainty in debris‐covered area produces changes in simulated discharge of about 5–6%. While there have a number of studies documenting the recession rates of midlatitude glaciers [e.g., Driedger and Kennard, 1986; Dodge, 1987; Oerlemans, 2005; Lillquist and Walker, 2006], the limited number of studies on debris‐covered zones show that they are less sensitive to climate change than debris‐free glaciers [Mayer et al., 2006; Mihalcea et al., 2008]. [47] In data sparse glacierized watersheds, the combination of discharge measurements and isotopic tracers is a valuable approach for making quantitative estimates of present‐day glacier melt contributions to streamflow and the temperature‐ index modeling approach, when accompanied by sensitivity analyses, can provide useful qualitative estimates of future glacier melt contributions to streams. ...
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1] While the impacts of long‐term climate change trends on glacier hydrology have received much attention, little has been done to quantify direct glacier runoff contributions to streamflow. This paper presents an approach for determining glacier runoff contributions to streamflow and estimating the effects of increased temperature and decreased glacier area on future runoff. We focus on late summer streamflow (when flow is lowest and nonglacier contributions to flow are minimal) of a small glacierized watershed on the flanks of Mount Hood, Oregon, United States. Field and lab measurements and satellite imagery were used in conjunction with a temperature‐index model of glacier runoff to simulate potential effects of increased temperature and reduction in glacier area on late summer runoff in the watershed. Discharge and stable isotope data show that 41–73% of late summer streamflow is presently derived directly from glacier melt. Model simulations indicate that while increased temperature leads to rapid glacier melt and therefore increased streamflow, the consequences of glacier recession overcomes this effect, ultimately leading to substantial declines in streamflow. Model sensitivity analyses show that simulation results are most sensitive to degree day factor and less sensitive to uncertainties in debris‐covered area and accumulation area ratio. This case study demonstrates that the effects of glacier recession on streamflow are a concern for water resource management at the local scale. This approach could also be extended to larger scales such as the upper Columbia River basin where glacier contributions to late summer flows are also thought to be substantial.
... The ice in MH and GNP is estimated to have been deposited a maximum of 7000 years ago, but peaked in the mid-1800s during the Little Ice Age [30,[35][36][37]. Therefore, the ice remaining today is likely a few hundred years old and is isotopically distinct from modern day precipitation. ...
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The importance of glacier meltwater as a source of mountain-block recharge remains poorly quantified, yet it may be essential to the integrity of alpine aquatic ecosystems by maintaining baseflow in streams and perennial flow in springs. We test the hypothesis that meltwater from alpine glaciers is a critical source of recharge for mountain groundwater systems using traditional stable isotopic source-identification techniques combined with a novel application of microbial DNA. We find that not only is alpine glacier meltwater a critical source of water for many springs, but that alpine springs primarily supported by glacial meltwater contain microbial taxa that are unique from springs primarily supported by seasonal recharge. Thus, recharge from glacial meltwater is vital in maintaining flow in alpine springs and it supports their distinct microbiomes.
... Alpine glaciers represent important sources of water for watersheds supporting agricultural and drinking water sources through summer dry periods in the Pacific Northwest (PNW), with glacial melt contributions of 41-73% for streams and rivers sourced from Mt. Hood, OR (Nolin et al., 2010). PNW glaciers have experienced rapid retreat over the last century (Lillquist and Walker, 2006), with predictions that 77% of PNW glaciers will not survive in the current and predicted climate (Pelto, 2010), making the study of these endangered systems imperative before they are gone. ...
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Earth has experienced periodic local to global glaciation for nearly 3 billion years, providing supra- and subglacial environments for colonization by microbial communities. A number of studies have reported on the role of microbial communities in glacial ecosystems including their influence on element cycling and weathering, but there is a paucity data on volcanic rock-hosted glacial ecosystems. Glaciers on stratovolcanoes in the Pacific Northwest override silica-rich rocks which represent analogues to an early Martian cryosphere. On these glaciers, blooms of photosynthetic snow algae support supraglacial microbial communities as has been observed on snowfields, glaciers, and ice sheets. In subglacial environments of volcanic rock-hosted glacial systems, weathering is driven, at least in part, by carbonic acid, suggesting a link between supraglacial carbon sources and subglacial heterotrophic microbial communities. Here, we report inorganic carbon assimilation and microbial community composition on glaciers across three stratovolcanoes ranging in composition from dacitic to mafic in the Pacific Northwest of the United States to begin to constrain the role of supraglacial primary productivity in subglacial weather processes. These data, coupled to contextual carbon and nitrogen isotope analyses of biomass and aqueous geochemistry, indicate snow algae drive light dependent carbon uptake across supraglacial and periglacial environments. Furthermore, snow algae microbial communities are supported by fixed nitrogen predominantly from deposition via precipitation. Our data highlight intense cycling of carbon and nitrogen driven by supraglacial microbial communities that feeds subglacial microbial communities which in turn may drive weathering processes. These results further underscore the role of glacial ecosystems in global biogeochemical cycling, especially during past global glaciations. Finally, these results lend support for glaciers as refugia for biodiversity on Earth and potentially on other bodies such as Mars where evidence exists for widespread and long-lived cryosphere including glaciers and ice sheets.
... The partial destruction of glaciers during subglacial volcanic eruptions is relatively common 347 (Supplementary Table 1), and typically involves glacier beheading (i.e., the destruction of part of a 348 glacier's accumulation zone). For example, White River Glacier, now Coalman Glacier, was partially 349 beheaded during an eruption of Mount Hood between 1894 and 1912 (Lillquist and Walker, 2006). Helens (Brugman and Post, 1981) (Fig. 5). ...
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Volcanic activity can have a notable impact on glacier behaviour (dimensions and dynamics). This is evident from the palaeo-record, but is often difficult to observe for modern glaciers. However, documenting and, if possible, quantifying volcanic impacts on modern glaciers is important if we are to predict their future behaviour (including crucial ice masses such as the West Antarctic Ice Sheet) and to monitor and mitigate glacio-volcanic hazards such as floods (including jökulhlaups) and lahars. This review provides an assessment of volcanic impacts on the behaviour of modern glaciers (since AD 1800) by presenting and summarising a global dataset of documented examples. The study reveals that shorter-term (days-to-months) impacts are typically destructive, while longer-term (years-to-decades) are more likely protective (e.g., limiting climatically driven ice loss). However, because these events are difficult to observe, particularly before the widespread availability of global satellite data, their frequency and importance are likely underestimated. The study also highlights that because the frequency and nature of volcano-glacier interactions may change with time (e.g., glacier retreat may lead to an increase in explosive volcanic activity), predicting their future importance is difficult. Fortunately, over coming years, continued improvements in remotely sensed data will increase the frequency, and enhance the quality, of observations of volcanic impacts on glaciers, allowing an improved understanding of their past and future operation.
... Five irrigation districts along the East, Middle, and West Forks of the Hood River rely on late summer snow and ice melt from six glaciers, along with reservoir storage of winter rains, to meet heavy water demands during the dry summer months, while maintaining sufficient instream flows and cool water temperatures for threatened fish. However, recent studies document that Mount Hood's glaciers, crucial to the water supply of the region, have decreased as much as 61% over the past century (Lillquist and Walker, 2006). Until this study, there were no monitoring programs to provide measurements of the contributions of Mt. ...
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northeast flanks of Mount Hood Oregon. Discharge measurements and isotope samples were used to calculate glacier meltwater contributions to the entire catchment, which feeds into a major diversion used for farmland irrigation. Data was primarily collected in August - September of 2007 because this is a period of little rain and suspected high glacier melt contributions. Discharge measurements taken at the termini of the Coe and Eliot Glaciers indicate a contribution of 40% of the entire catchment's runoff between August 10 and September 7. Isotopic analyses, which include the inputs of all other glacier surfaces in the catchment, show a total glacier contribution of 62 - 74% of catchment discharge at a given time. The Snowmelt Runoff Model (SRM) was calibrated using the 2007 discharge records to quantify August - September glacier runoff in the Middle Fork catchment under a variety of scenarios. SRM simulations indicate that runoff from the catchment glaciers are highly sensitive to changes in glacial area, debris-cover, and air temperatures. The decrease in discharge due to glacier recession is measured to be higher than the effect of forecasted temperature increases, implying that annual glacier runoff is decreasing over time. Applying current glacier recession rates and a 2°C temperature forcing, the model predicts a decrease of 31.3% of late summer glacier runoff by 2059, most of which is lost in August. This study suggests that glaciers currently play a significant hydrological role in the upper catchments of the Hood River Basin at a time when water is needed most, and that these contributions will diminish over time. Complete results are available in Phillippe's Masters thesis. PROJECT DESCRIPTION AND RESULTS: The objectives of this work were to determine if glacier meltwater makes a significant contribution to streamflow in the Upper Middle Fork Hood River and how future glacier melt contributions might change on timescales of 10-50 years.
... The nearest long-term meteorological record is from Diablo Dam ( It is quite common in the glaciological literature to find decadal climate variability invoked as the cause of glacier variability on these timescales (e.g. Hodge and others, 1998;Moore and Demuth, 2001;Kovanen, 2003;Nesje and Dahl, 2003;Pederson and others, 2004;Lillquist and Walker, 2006). In particular, for the Pacific Northwest, much is made of the Pacific Decadal Oscillation (PDO). ...
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Decadal-scale climate variations in the Pacific Ocean wield a strong influence on the oceanic ecosystem. Two dominant patterns of large-scale SST variability and one dominant pattern of large-scale thermocline variability can be explained as a forced oceanic response to large-scale changes in the Aleutian Low. The physical mechanisms that generate this decadal variability are still unclear, but stochastic atmospheric forcing of the ocean combined with atmospheric teleconnections from the tropics to the midlatitudes and some weak ocean-atmosphere feedbacks processes are the most plausible explanation. These observed physical variations organize the oceanic ecosystem response through large-scale basin-wide forcings that exert distinct local influences through many different processes. The regional ecosystem impacts of these local processes are discussed for the Tropical Pacific, the Central North Pacific, the Kuroshio-Oyashio Extension, the Bering Sea, the Gulf of Alaska, and the California Current System regions in the context of the observed decadal climate variability. The physical ocean-atmosphere system and the oceanic ecosystem interact through many different processes. These include physical forcing of the ecosystem by changes in solar fluxes, ocean temperature, horizontal current advection, vertical mixing and upwelling, freshwater fluxes, and sea ice. These also include oceanic ecosystem forcing of the climate by attenuation of solar energy by phytoplankton absorption and atmospheric aerosol production by phytoplankton DMS fluxes. A more complete understanding of the complicated feedback processes controlling decadal variability, ocean ecosystems, and biogeochemical cycling requires a concerted and organized long-term observational and modeling effort.
Article
The relations between seasonal changes in ice speed, longitudinal extension rate and terminus position are investigated for Columbia Glacier, Alaska, over the period 1977–87. The lower reach of the glacier is studied using repeat aerial photography, which extends from the terminus to the base of an icefall about 14 km up-glacier. There are regular seasonal cycles in speed and stretching rate. These cycles continue after the glacier retreats off the shoal at the end of the fjord (in about 1983), indicating that factors other than backstress, such as seasonal changes in subglacial water, control the speed of the glacier. Terminus position appears to be linked with thinning induced by longitudinal extension, as predicted by the calving model proposed by Van der Veen (1996).
Article
A simple model suggests that the ablation under a debris layer could be estimated from meteorological variables if the surface temperature data of the layer are available. This method was tested by analyzing the data obtained from experiments with artificial debris layers. Fairly good agreement was obtained between the estimated and the experimental data.
Article
Numerous moraines front the Coe Glacier on the north side of Mount Hood, Oregon. These moraines were identified and dated using a multiple methodology approach in order to establish a chronology for the advances and stillstands of the Coe Glacier. This chronology was compared to chronologies established for other glaciers on Mount Hood, North Sister, Mount Rainier and Mount Baker as well as glaciers in Scandinavia. The chronology was also compared to a long- term temperature record from Longmire, Washington. -from Author
Article
Within the last 10 000 years, three significant lahar-producing periods have occurred at Mount Hood, Oregon. The Timberline eruptive period occurred between 1400 and 1800 years BP. It was by far the most voluminous of the three periods, producing enough clastic debris to bury the glacial topography of the southwest face of the mountain beneath a smooth debris fan. Timberline-age lahars traveled the length of the Zigzag and Sandy Rivers, a distance in excess of 90 km. Between 400 and 600 years BP, the Zigzag eruptive period produced deposits along the middle reaches of the Zigzag River and the upper Sandy River. The Old Maid eruptive period occurred between 180 and 270 years BP. A single lahar flowed down the Sandy River at least as far as Brightwood, 30 km from Crater Rock. -from Authors
Article
Cascade Range alpine glaciers have shrunk substantially as average annual temperature has risen 0.5 to 2 degrees Celsius since culmination of the Little Ice Age in the mid- to late 1800's. In recently deglaciated areas in the Cascade Range, hundreds of lakes have formed. Most of these newly formed lakes are partly or entirely bound by bedrock rims and are stable, but at least 30 are dammed by unconsolidated moraines that are susceptible to breaching. The highest concentration of lakes dammed by Neological moraines in the conterminous United States is in the Mount Jefferson and Three Sisters Wilderness Areas in central Oregon, where there are currently eight moraine-dammed lakes. The largest lake, Carver Lake on South Sister, has a volume of almost 1 million cubic meters. Most of these lakes formed between 1920 and 1940 during a period of substantial warming and glacier retreat. In the Mount Jefferson and Three Sisters Wilderness Areas, there have been 11 debris flows from 4 complete and 7 partial emptyings of moraine-dammed lakes. Most of these breaches occured between 1930 and 1950, but some were as recent as the 1970's. All moraine-dam breaches in the Three Sisters and Mount Jefferson Wilderness Areas occurred during the melt season (July-October), usually during periods of warm or rainy weather. Many breaches were probably a result of erosion of the steep outlet channels, triggered by unusually large discharges caused by (1) waves generated by rockfalls or ice avalanches into the lake or (2) increased lake outflow caused by precipitation and melting snow and ice. Water flows from breached moraine dams rapidly evolved into debris flows that traveled as far as 9 kilometers before stopping or evolving into sediment-laden water flows. Peak discharges of at least four of the flows exceeded 300 cubic meters per second. Flows from breached morainal dams transformed from clear water at the outlet into debris flows within 500 meters of the breaches by incorporating large volumes of loose Neoglacial till and outwash from the moraines and proglacial outwash. For the two largest lake releases, the volume of sediment eroded near the outlet exceeded 25 percent of the total volume of water released. Morphological evidence indicates that sediment was introduced into flows by bank collapse and channel incision. Indirect discharge estimates (primarily by a critical-depth procedure) show that peak discharges increased in erosional reaches; in one instance by more than a factor of four. Erosion and sediment entrainment was restricted to reaches with slopes that exceeded 8°, and deposition occured in reaches with slopes less than 18°. Several moraine-dammed lakes still exist, and some pose downstream hazards. Two of the lakes are remnants of previously larger lakes that have partially breached their moraine dams. Five lakes in the Three Sisters and Mount Jefferson Wilderness Areas are impounded by Neoglacial moraines that have not been breached. Qualitative assessments of downstream hazards from moraine-dammed lakes are possible on the basis of the topographic setting of the lake and downstream channel conditions. Quantitative assessment of the likelihood of breaching or the magnitude of downstream flows is difficult because of the variety of mechanisms that trigger breaches, the sensitivity of outflow hydrographs to breach shape and erosion rate, and the large uncertainty of downstream flow characteristics.
Article
Contemporaneous correlations between geopotential heights on a given pressure surface at widely separated points on earth, referred to as teleconnections in this paper, are studied in an attempt to identify and document recurrent spatial patterns which might be indicative of standing oscillations in the planetary waves during the Northern Hemisphere winter, with time scales on the order of a month or longer. -from Authors
Article
The leading empirical orthogonal function of the wintertime sea-level perssure field is more strongly coupled to surface air temperature fluctuations over the Eurasian continent than the North Atlantic Oscillation (NAO). It resembles the NAO in many respects; but its primary center of action covers more of the Arctic, giving it a more zonally symmetric appearance. Coupled to strong fluctuations at the 50-hPa level on the intraseasonal, interannual, and interdecadal time scales, this 'Arctic Oscillation' (AO) can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft. It is proposed that the zonally asymmetric surface air temperature and mid-tropospheric circulation anomalies observed in association with the AO may be secondary baroclinic features induced by the land-sea contrasts. The same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature, sea-level pressure, and 50-hPa height over the past 30 years: parts of Eurasia have warmed by as much as several K, sea-level pressure over parts of the Arctic has fallen by 4 hPa, and the core of the lower stratospheric polar vortex has cooled by several K. These trends can be interpreted as the development of a systematic bias in one of the atmosphere's dominant, naturally occurring modes of variability.
Article
Despite the complex interrelationships between climate, mass balance, and glacier response, simplified mass-balance calculations can be correlated with observed glacial behavior. A monthly temperature and precipitation record, extending back to 1850, has been reconstructed for Longmire, Washington, on the southwest flank of Mount Rainier. Calculated mass-balance variations agree with observed glacier behavior since 1850 and with five sets of moraines constructed between 1850 and 1930 at Mount Rainier. Following periods of positive mass balances, trends toward more negative mass balances precede glacial recession with lag times of 1 to 5 yr. Analyses of the reconstructed temperature record and former ice frontal positions suggest that much of a 1°C temperature rise since the latest Neoglacial advances occurred prior to 1850. Correlations of the Mount Rainier mass-balance record with similar ones from Norway and Antarctica indicate generally synchronous climatic trends in the Northern Hemisphere and opposing short-term trends in the Southern Hemisphere since 1850.
Article
A compilation of terminus variation data from the early 19th century to 1987 is provided for Blue Glacier, the largest of 266 glaciers in the Olympic Mountains, Washington. Sources of the data include field studies of Neoglacial moraines and trimlines; written accounts and mountaineering photographs from 1890 to 1942; oblique and vertical aerial photography taken intermittently from 1955 to 1982; two topographic maps and four glacier maps (1939, 1952, 1957, 1979); and nearly annual field measurement of the glacier terminus from 1938 to the present. -from Author
Article
The terminus positions of six glaciers located on Mount Baker, Washington, were mapped by photogrammetric techniques at 2- to 7-yr intervals for the period 1940-1990. Although the timing varied slightly, each of the glaciers experienced a similar fluctuation sequence consisting of three phases: (1) rapid retreat, beginning prior to 1940 and lasting through the late 1940s to early 1950s; (2) approximately 30 yr of advance, ending in the late 1970s to early 1980s; (3) retreat though 1990. Terminus positions changed by up to 750 m during phases, with the advance phase increasing the lengths of glaciers by 13 to 24%. These fluctuations are well explained by variations in a smoothed time-series of accumulation-season precipitation and ablation-season mean temperature. The study glaciers appear to respond to interannual scale changes in climate within 20 yr or less. The glaciers on Mount Baker have a maritime location and a large percentage of area at high elevation, which may make their termini undergo greater fluctuations in response to climatic changes, especially precipitation variations, than most other glaciers in the North Cascades region.
Article
Fluctuations of glacier termini were studied in two regions in Alaska. In the Wrangell Mountains, 15 glaciers on Mount Wrangell, an active volcano, have been monitored over the past 30 years by surveying, photogrammetry and satellite. Results, which are consistent between different methods of measurement, indicate that the termini of most glaciers were stationary or retreating slightly. However, the termini of the 30 km long Ahtna Glacier and the smaller Center and South MacKeith Glaciers began to advance in the early 1960s and have advanced steadily between 5 and 18 m a ⁻¹ since then. These three glaciers flow from the active North Crater, where increased volcanic heating since 1964 has melted over 7 x 10 ⁷ m ³ of ice. We suspect that volcanic meltwater has changed the basal conditions for the three glaciers, resulting in their advance. The terminus fluctuations of six tide-water and near-tide-water glaciers in College Fjord, Prince William Sound, have been monitored since 1931 by surveying, photogrammetry and, most recently, by satellite imagery. Harvard Glacier, a 40 km long tide-water glacier, has been advancing at an average rate of nearly 20 ma ⁻¹ since 1931, while the adjacent Yale Glacier has retreated at approximately 50 ma ⁻¹ during the same period though, for short periods, both of these rates have been much higher. The striking contrast between the terminus behavior of Yale and Harvard Glaciers, which parallel each other in the same fiord, and are derived from the same snowfield, supports the hypothesis that their terminus behavior is largely the result of dynamic controls rather than changes in climate.
Article
A simple model suggests that the ablation under a debris layer could be estimated from meteorological variables if the surface temperature data of the layer are available. This method was tested by analyzing the data obtained from experiments with artificial debris layers.-from Authors
Article
Two models based on standard observations of precipitation, temperature, and run-off at low-altitude weather and gaging stations have been devised to calculate annual glacier balances in the North Cascades of Washington. The predicted glacier balances of the Thunder Creek basin glaciers, determined by a run-off–precipitation (RP) model during the 1920–74 period, are compared with balances predicted by a precipitation–temperature (PT) model for the same period. Annual balances determined by the PT model are also compared with balances measured by field techniques at South Cascade Glacier since 1958. In the PT model, winter snow accumulation (winter balance) is determined by winter (October–April) precipitation observed at the Snoqualmie Falls weather station. Summer (May–September) ablation (summer balance) on the glaciers is estimated by a technique which utilizes maximum and minimum air temperatures, also observed at Snoqualmie Falls. Ablation calculations incorporate summer cloud cover as a variable by using a relationship between cloud cover and the range in daily maximum and minimum air temperatures. Annual mass changes for the 1884–1974 period in both South Cascade Glacier and the Thunder Creek glaciers were reconstructed by utilizing the PT model. The fluctuations in glacier mass during this period generally agree with historical observations and show that a definite change in glacier activity from marked recession to stability or an advancing state occurred about 1945. During the 1900–45 period, South Cascade Glacier lost mass at a rate of 1.4 m per year and the Thunder Creek glaciers (which are at a higher altitude) at 1.1 m per year. These models suggest that the relationship of glacier mass balance to precipitation and temperature is a very sensitive one. It appears from these studies that a decrease in summer air temperature of just over 0.5 deg or an increase in winter accumulation of slightly more than 10% (350 mm) from the 1920–74 average would cause these glaciers to grow continuously.
Article
The relations between seasonal changes in ice speed, longitudinal extension rate and terminus position are investigated for Columbia Glacier, Alaska, over the period 1977-87. The lower reach of the glacier is studied using repeat aerial photography, which extends from the terminus to the base of an icefall about 14 km up-glacier. There are regular seasonal cycles in speed and stretching rate. These cycles continue after the glacier retreats off the shoal at the end of the fjord (in about 1983), indicating that factors other than backstress, such as seasonal changes in subglacial water, control the speed of the glacier. Terminus position appears to be linked with thinning induced by longitudinal extension, as predicted by the calving model proposed by Van derVeen (1996).
Article
The most recent eruptive period of Mount Hood volcano, the Old Maid eruptive period, was characterized by volcano-hydrologic events (hydrologic events initiated by volcanic activity) which resulted in extensive lahar inundation in the White, Sandy, and Zigzag River drainages and produced a lithic pyroclastic flow which traveled at least 9 km down the White River from the vent area at Crater Rock. Interpretations of downstream textural changes in deposits indicate that one lahar reached as far as Tygh Valley (65 km from the vent) before transforming into a lahar runout (hyperconcentrated flow). The runout inundated Tygh Valley and flowed into the Deschutes River, 75 km (flow path) from the volcano. A single lahar traveled more than 30 km down the Sandy River before transforming to a runout. Correlative sands and gravels are found as far as the apex of the Sandy River delta, more than 80 km from the volcano; these suggest that the flow underwent minimal attenuation of stage height throughout the length of Sandy River. Approximate dates ranging from 1760 A.D. to 1810 A.D. for various Old Maid-age events are inferred from dendrochronologic studies of old growth trees. There have been no apparent major topographic changes in the vent area since the end of Old Maid-age activity, enabling the events of the Old Maid eruptive period to be used as a model for future eruptive activity.
Article
High Cascade volcanoes include all those formed along the Cascade trend during the Pliocene, Pleistocene, and Recent epochs. They have extruded lavas ranging from basalt to rhyolite, but dominantly andesite. The products of this intense period of volcanism were studied i n a 300-square-mile area surrounding and including Mt. Hood, Oregon. The object of the study was to obtain field and geochemical evidence bearing on the origin of andesitic magmas. The High Cascade lavas of the Mt. Hood area were erupted onto a surface formed by the Miocene Yakima Basalt. Late Miocene activity was mild, producing a few scattered andesite volcanoes. These centers of activity shed epiclastic and pyroclastic debris into basins on each side of the emerging mountain belt. Volcaniclastic debris and interbedded flows accumulated to local thicknesses near 1400 feet before Pliocene time. Early Pliocene activity was intense; andesite was erupted from several centers and locally accumulated to thicknesses of several thousand feet. A few basalt flows preceded the andesites and may be genetically related to the far more voluminous olivine andesite and pyroxene andesite. A shallow pluton of quartz-diorite was intruded into some of these lavas during the late part of this period. Two late Pliocene volcanic centers erupted sequences of olivine basalt, olivine andesite, and pyroxene andesite. Other centers erupted voluminous andesite not associated with basalts. The composite cone of the Mt. Hood volcano was built during late Pleistocene time. It is composed of olivine-, pyroxene-, and hornblende-dacite lavas and pyroclastic debris. Contemporaneous basalts and olivine andesites were erupted from many nearby vents, which are not directly connected with the Mt. Hood volcano. The main cone growth ceased before the Fraser Glaciation, but a plug-dome of hornblende andesite was extruded through the southern slope about 2000 years ago. Other late Pleistocene activity yielded flows of olivine basalt and olivine andesite. Several domes and flows of hornblende dacite were also extruded. Chemical analyses were obtained from 158 samples, for which relevant field relations are known. Plots of the Differentiation Index (normative Ab + An + Or + Qz) against lime, total alkalis, potash, and soda serve to characterize lavas from various eruptive centers. Andesites directly associated with high-alumina basalt contain significantly more potash than andesites not associated with basalts, such as those found at Mt. Hood. Field relations coupled with chemical data lead to the following conclusions: (1) the Mt. Hood lava did not differentiate from high-alumina basalt magma; (2) the Mt. Hood lavas are probably not a single series of magmas related by differentiation, but may be a series of similar magmas generated through time by some process, such as supracrustal anatexis; (3) olivine basalts magmas do differentiate to form andesite; (4) all olivine basalts in the Mt. Hood area were differentiated or contaminated prior to eruption; and (5) several recognizably different magma series were erupted through time - some are related to a basalt parent; others, to a primary andesite.
Article
Mount St. Helens has been more active and more explosive during the last 4500 years than any other volcano in the conterminous United States. Eruptions of that period repeatedly formed domes, large volumes of pumice, hot pyroclastic flows, and during the last 2500 years, lava flows. Some of this activity resulted in mudflows that extended tens of kilometers down the floors of valleys that head at the volcano. This report describes the nature of these phenomena and their threat to people and property; the accompanying maps show areas likely to be affected by future eruptions of Mount St. Helens. Explosive eruptions that produce large volumes of pumice affect large areas because winds can carry the lightweight material hundreds of kilometers from the volcano. Because of prevailing winds, the 180° sector east of the volcano will be affected most often and most severely by future eruptions of this kind. However, the pumice from any one eruption probably will fall in only a small part of that sector. Pyroclastic flows and mudflows also can affect areas far from the volcano, but the areas they affect are smaller because they follow valleys. Mudflows and possibly pyroclastic flows moving rapidly down Swift and Pine Creeks could displace water in Swift Reservoir, which could cause disastrous floods farther downvalley.
Article
The mass balance of glaciers depends on precipitation and temperature in winter and on temperature and insolation in summer. For glaciers in western North America these meteorological variables are influenced by the large-scale atmospheric circulation over the North Pacific Ocean. This study addresses the relation between mass balance at six glaciers in western North America and large-scale atmospheric effects at interannual time scales, and longer-term cumulative changes in glacier volume. Mass balance data for these glaciers spans 20 years (1966-1985). Similarities and differences between the mass balances are brought out by using empirical orthogonal function analysis. Almost 80 percent of the variance is contained in the first 2 empirical modes (61%, 17%). The first mode shows a negative correlation between the balances for the Alaska glaciers and for the other glaciers. This relation is due to the steering effect of the Aleutian/Gulf of Alaska Low; when it is dry in Washington it is usually wet in Alaska and vice versa. The first mode also shows that dry conditions in Washington and wet conditions in Alaska are associated with a positive Pacific North America (PNA) index and usually with El Niño/Southern Oscillation events. In addition, there was a several-year bias introduced after the 1977 ENSO event such that the mass balances in Washington were more negative, and those in Alaska were more positive than before. Over decade time scales the cumulative mass balances show an inverse relation between balance at the coastal Alaska glacier and at the southern glaciers. However, the overall trends display a different relation with negative trends at all glaciers except two in the coastal region of British Columbia and Alaska.
Article
ABSTRACT. Photogrammetric analysis of Eliot Glacier, Mount Hood, Oregon indicates an average thinning of the ablation area of 4.2 m during 1984-89. Thinning is generally more marked near the equilibrium line, where debris cover is absent, than on the lowest part of the glacier, where superglacial debris thickness is greater than 1.0 m. The pattern of glacier thickness change is partly related to the reduction of ablation with increasing debris thickness, though flow kinematics must also be important to change in ice thickness.
Article
The response time of temperate glaciers is estimated by the following continuity argument: The difference in the steady state ice volume of a glacier, before and after a mass balance perturbation must be accumulated (or ablated) before the glacier can reach a new steady state. This leads to a time scale which is termed the “volume time scale” of the glacier. It is argued that the response time of the glacier can be expected to be equal to the volume time scale. The volume time scale can be derived by a simple argument and is under fairly general conditions expressed by the formula Tv = H/(−bt) where H is a thickness scale of the glacier and bt is a scale of the ablation along the terminus of the glacier. This estimate of the response time of glaciers is of the order of decades for small maritime glaciers, which is in reasonable agreement with experience. This is much shorter than the theoretical long response time of the order of several hundred or a thousand years which has been derived in the past from kinematic wave theory.
Article
Non-climatically controlled fluctuations of glacier termini were studied in two regions in Alaska. In the Wrangell Mountains, eight glaciers on Mt. Wrangell, an active volcano, have been monitored over the past 30 years using terrestrial surveys, aerial photogrammetry and digitally registered satellite images. Results, which are consistent between different methods of measurement, indicate that the termini of most glaciers were stationary or had retreated slightly. However, the termini of the 30-km-long Ahtna Glacier and the smaller Center and South MacKeith glaciers began to advance in the early 1960s and have advanced steadily at rates between 5 and 18 m yr-1 since then. These three glaciers flow from the summit caldera of ML Wrangell near the active North Crater, where increased volcanic heating since 1964 has melted over 7 x 107 M3 of ice. The authors suspect that volcanic meltwater has changed the basal conditions for the glaciers, resulting in their advance. In College Fjord, Prince William Sound, the terminus fluctuations of two tidewater glaciers have been monitored since 1931 by terrestrial surveying, photogrammetry, and most recently, from satellite imagery. Harvard Glacier, a 40-kmlong tidewater glacier, has been advancing steadily at nearly 20 m yr-1 since 1931, while the adjacent Yale Glacier has retreated at approximately 50 m yr-1 during the same period, though for short periods, both rates have been much higher.
Article
The leading empirical orthogonal function of the wintertime sea-level pressure field is more strongly coupled to surface air temperature fluctuations over the Eurasian continent than the North Atlantic Oscillation (NAO). It resembles the NAO in many respects; but its primary center of action covers more of the Arctic, giving it a more zonally symmetric appearance. Coupled to strong fluctuations at the 50-hPa level on the intraseasonal, interannual, and interdecadal time scales, this “Arctic Oscillation” (AO) can be interpreted as the surface signature of modulations in the strength of the polar vortex aloft. It is proposed that the zonally asymmetric surface air temperature and mid-tropospheric circulation anomalies observed in association with the AO may be secondary baroclinic features induced by the land-sea contrasts. The same modal structure is mirrored in the pronounced trends in winter and springtime surface air temperature, sea-level pressure, and 50-hPa height over the past 30 years: parts of Eurasia have warmed by as much as several K, sea-level pressure over parts of the Arctic has fallen by 4 hPa, and the core of the lower stratospheric polar vortex has cooled by several K. These trends can be interpreted as the development of a systematic bias in one of the atmosphere's dominant, naturally occurring modes of variability.
Article
Between 1953 and 1955, 73 glaciers in the Olympic and Cascade Mountains of Washington State have been investigated to determine their present activity. 50 of these glaciers are now advancing at rates from 3 to 100 m. or more per annum. Of the remaining 23, 22 glaciers either demonstrate clear evidence of increasing thickness, or have remained so heavily snow-covered at the end of the ablation season that it has not been possible to locate their limits. The present glacier growth, which appears to have started about 12 years ago, represents a radical change from conditions during the previous 20 years when glaciers of the Olympics and Cascades without exception were shrinking rapidly. An analysis of local climatic data demonstrates a present trend toward a cooler, wetter climate in western Washington. The ten year running mean annual temperature at Tatoosh Island off the Washington coast has decreased approximately o 8° C. from the period 1934–1943 to the period 1945–1954. In the same interval of time the ten year running mean annual precipitation at Tatoosh has increased about 38 cm., and during the last decade has reached its highest value since the period 1898–1907.
Article
Using satellite data, the longitudinal distribution of the ablation rate and flow velocity were estimated for the ablation area, where glacier ice is covered with supraglacial debris. The ablation rate, small around Everest Base Camp (EBC) just below the equilibrium line, increased down-glacier for about 3 km, then decreased gradually toward the apparent terminus, located about 10 km from EBC. The velocity decreased almost linearly from EBC to the terminus. The results allowed estimation of the recent change of ice thickness using the continuity equation. The glacier has thinned recently in the ablation area. The rate of thinning was large near EBC, where the surface is either bare ice or covered with very thin debris cover, but relatively small and rather uniform at lower sites, where the supraglacial debris layer was thick and supraglacial lakes and ice cliffs predominate. The general pattern is compatible with field observations.
Article
Climate variability in the Pacific basin has been attributed to large-scale oceanic-atmospheric modulations (e.g. the El Niño-Southern Oscillation (ENSO)) that dominate the weather of adjacent land areas. The Pacific Decadal Oscillation (PDO) and north Pacific index are thought to be indicators of modulations and events in the northeast Pacific. In this study we find that variations in the PDO are reflected in the terminus position of glaciers on Mt Baker, in the northern Cascade Range, Washington. The initiation of retreat and advance phases of six glaciers persisted for 20–30 years, which relate to PDO regime shifts. The result of this study agrees with previous studies that link glacier mass balance changes to local precipitation anomalies and processes in the Pacific. However, the use of mass balance changes and glacier terminus variation for identification of regime shifts in climate indices is complicated by the lack of standardized measuring techniques, differing response times of individual glaciers to changes in climate, geographic and morphometric factors, and the use of assorted climate indices with different domains and time-scales in the Pacific for comparison.
Article
Since 1984, annual glacier mass balance measurements have been conducted on eight glaciers by the North Cascades Glacier Climate Project (NCGCP). Since 1993 the National Park Service (NPS) has monitored the mass balance of four glaciers, and the NCGCP an additional two glaciers. This 14 glacier monitoring network, covering an area of 14 000 km², represents the most extensive network of mass balance measurements for alpine glaciated areas in the world. The breadth of the record allows determination of the annual variability of annual balance from glacier to glacier, and from year to year.
Conference Paper
It is a great concern for the Research Committee (JAARC) to keep close contact with the industry. In the past, it was the usual practice for this Committee to organise a general open day, in order to present our work and to obtain feedback. Breakout sessions were organised on the different fields (among which was Human Factors). However, this was not alltogether successful as some organisations were not able to send enough people to attend all the breakout sessions they were interested in. This is the reason why the RC asked this year the Project Advisory Groups (PAGs) to organise specific open days.
Article
The nature and rate of the transition from a thinning, melting ablation zone to a retreating, calving terminus is examined at the debris-mantled Tasman Glacier. The debris mantle has existed since the earliest glaciological observations were made in 1863, indicating that debris cover is the normal glaciological state regardless of historic mass-balance change. The relationship between debris thickness and ablation rate has been derived from short-term heat flow calculations. Extrapolation over time and space indicate that the thermal effect of the debris mantle has resulted in a post-1890 reduction in glacier surface gradient which, through positive feedback involving ablation rate, ice velocity and particle emergence paths, has caused upglacier spread of supraglacial debris and upstream migration of the locus of maximum ablation. This has lead to the preservation of a long ice tongue at low gradient while preventing terminus retreat from the outwash head, and has made the glacier vulnerable to calving. Since the late 1970s, thermokarst melting has formed an ice-contact proglacial lake in which water depths now exceed ca. 130 m against the ice front. Since 1994, evidence of extending and accelerating flow may indicate the imminent onset of rapid calving. Predicted retreat scenarios suggest a rapid retreat of at least 10 km will probably cause major (possibly catastrophic) rock and debris avalanches into the enlarging proglacial lake as debuttressing of mountainsides progresses.
Article
The edifice of Mount Rainier, an active stratovolcano, has episodically collapsed leading to major debris flows. The largest debris flows are related to argillically altered rock which leave areas of the edifice prone to failure. The argillic alteration results from the neutralization of acidic magmatic gases that condense in a meteoric water hydrothermal system fed by the melting of a thick mantle of glacial ice. Two craters atop a 2000-year-old cone on the summit of the volcano contain the world's largest volcanic ice-cave system. In the spring of 1997 two active fumaroles (T=62°C) in the caves were sampled for stable isotopic, gas, and geochemical studies.
Article
As glacier length fluctuations provide useful information about past climate, we derived historic fluctuations in the equilibrium-line altitude (ELA) on the basis of 19 glacier length records from different parts of the world. We used a model that takes into account the geometry of the glacier, the length response time and the mass balance-surface height feedback. The results show that all glaciers of the data set experienced an increase in the ELA between 1900 and 1960. Between 1910 and 1959, the average increase was 33 ± 8 m. This implies that during the first half of the 20th century, the climate was warmer or drier than before. The ELAs decreased to lower elevations after around 1960 up to 1980, when most of the ELA reconstructions end. These results can be translated into an average temperature increase of 0.8 ± 0.2 K and a global sea-level rise of about 0.3 mm a-1 for the period 19/0-/959.
The glaciers of Mt. Hood and Mt. Adams.
  • H. F. Reid
Reid, H. F., 1905: The glaciers of Mt. Hood and Mt. Adams. Mazama, 2: 194-200.
The Guardians of the Columbia. Tacoma: John H. Williams, 142 pp
  • J. H. Williams
Williams, J. H., 1912: The Guardians of the Columbia. Tacoma: John H. Williams, 142 pp.
Recent survey of Coe and Eliot Glaciers.
  • R. S. Mason
Mason, R. S., 1954: Recent survey of Coe and Eliot Glaciers. Mazama, 36: 37-39.
The Eliot Glacier: New methods and some interpretations.
  • N. A. Dodge
Dodge, N. A., 1971: The Eliot Glacier: New methods and some interpretations. Mazama, 53: 25-29.